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HJ 666-2013: Water quality. Determination of ammonium nitrogen by flow injection analysis (FIA) and Salicylic acid spectrophotometry
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Water quality. Determination of ammonium nitrogen by flow injection analysis (FIA) and Salicylic acid spectrophotometry
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HJ 666-2013
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Basic data | Standard ID | HJ 666-2013 (HJ666-2013) | | Description (Translated English) | Water quality. Determination of ammonium nitrogen by flow injection analysis (FIA) and Salicylic acid spectrophotometry | | Sector / Industry | Environmental Protection Industry Standard | | Classification of Chinese Standard | Z16 | | Classification of International Standard | 13.060 | | Word Count Estimation | 10,176 | | Quoted Standard | HJ 536; HJ/T 91; HJ/T 164 | | Regulation (derived from) | Ministry of Environmental Protection Notice No. 63 of 2013 | | Issuing agency(ies) | Ministry of Ecology and Environment | | Summary | This standard specifies the determination of ammonia in water flow injection analysis - spectrophotometry. This standard applies to surface water, groundwater, sewage and industrial measurement WASTEWATER. When detecting the optical path is 10mm, the meth | HJ 666-2013: Water quality. Determination of ammonium nitrogen by flow injection analysis (FIA) and Salicylic acid spectrophotometry
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Water quality.Determination of ammonium nitrogen by flow injection analysis (FIA) and Salicylic acid spectrophotometry
National Environmental Protection Standard of the People's Republic
Determination of ammonia nitrogen in water quality
Flow injection-salicylic acid spectrophotometry
Water quality-Determination of ammonium nitrogen by flow injection
Analysis (FIA) and Salicylic acid spectrophotometry
Published on.2013-10-25
2014-01-01 implementation
Ministry of Environmental Protection released
Content
Foreword. II
1 Scope..1
2 Normative references..1
3 method principle..1
4 Interference and elimination.1
5 reagents and materials. 2
6 instruments and equipment.2
7 samples.3
8 Analysis steps..3
9 Calculation and representation of results..3
10 precision and accuracy..4
11 Quality Assurance and Quality Control.4
12 Notes. 5
Foreword
To implement the Environmental Protection Law of the People's Republic of China and the Law of the People's Republic of China on Water Pollution Prevention and Control, to protect the environment,
To ensure human health, standardize the determination method of ammonia nitrogen in water, and formulate this standard.
This standard specifies a flow injection-salicylic acid spectrophotometric method for the determination of ammonia nitrogen in water.
This standard is the first release.
This standard was formulated by the Science and Technology Standards Department of the Ministry of Environmental Protection.
This standard is mainly drafted by. Suzhou Environmental Monitoring Center Station and Changshu Environmental Monitoring Station.
This standard is verified by. Water Quality Testing Center of Suzhou Water Supply Company, Nantong Environmental Monitoring Center Station, Jiangsu Province Sea
Ocean Fisheries Research Institute, Nanchang Environmental Monitoring Station, East China Normal University Hekou Coastal Science Research Institute and Changshu Environmental Monitoring Station.
This standard was approved by the Ministry of Environmental Protection on October 25,.2013.
This standard has been implemented since January 1,.2014.
This standard is explained by the Ministry of Environmental Protection.
Water quality - Determination of ammonia nitrogen - Flow injection - salicylic acid spectrophotometric method
1 Scope of application
This standard specifies the flow injection analysis-spectrophotometry for the determination of ammonia nitrogen in water.
This standard applies to the determination of ammonia nitrogen in surface water, groundwater, domestic sewage and industrial wastewater.
When the detection optical path is 10mm, the detection limit of this method is 0.01mg/L (in N), and the measurement range is
0.04mg/L~5.00mg/L.
2 Normative references
The contents of this standard refer to the terms in the following documents. For undated references, the valid version applies to
This standard.
HJ 536 Water quality - Determination of ammonia nitrogen - Salicylic acid spectrophotometric method
HJ/T 91 Surface Water and Wastewater Monitoring Technical Specifications
HJ/T 164 Technical Specifications for Groundwater Environmental Monitoring
3 Principle of the method
3.1 Working principle of flow injection analyzer
In a closed pipeline, a volume of sample is injected into a continuous flow of carrier liquid, and the sample and reagent are in a chemical reaction mode.
The blocks are mixed and reacted in a specific order and proportion. Under the condition of incomplete reaction, the flow detection cell is entered for photometric inspection.
Measurement.
3.2 Principles of chemical reactions
In an alkaline medium, ammonia and ammonium ions in the sample react with hypochlorite to form chloramine. At 60 ° C and nitrosyl cyanide
In the presence of potassium, chloramine reacts with salicylate to form a blue-green compound, and the absorbance is measured at a wavelength of 660 nm.
Refer to the work flow chart, as shown in Figure 1.
1-peristaltic pump 2 - injection valve 3 - reaction (mixing) ring 4 - heating pool (ring) 60 ° C
5-detection cell 10mm, 660nm R1-buffer solution (5.10) R2-chromogen (5.11) R3-sodium hypochlorite solution (5.12)
S-sample C-carrier liquid W-waste liquid
Figure 1 Flow chart of flow injection-salicylic acid spectrophotometric determination of ammonia nitrogen
4 interference and elimination
4.1 The residual chlorine in the sample will form a chloramine interference assay, which can be removed by adding an appropriate amount of sodium thiosulfate solution (5.15).
4.2 When the concentration of iron and manganese ions in the sample is greater than 500mg/L and 35mg/L, respectively, it will cause positive interference to the analysis;
The turbidity or color can interfere with the measurement. The sample can be pre-distilled with reference to HJ 536. Calcium and magnesium ions in the sample
When the chloride ion concentration is not more than 900 mg/L, 1000 mg/L and 100000 mg/L, respectively, there is no effect on the determination of ammonia nitrogen.
4.3 When the pH of the sample is >12 or pH< 1, the pH of the sample should be adjusted to neutral before analysis. Samples preserved with acid are easily absorbed
Ammonia in the air affects the measurement results and should be kept in a closed state.
5 reagents and materials
Unless otherwise stated, analytically pure reagents that meet national standards were used for the analysis. Experimental water is freshly prepared, resistor
Ammonia-free water with a rate greater than 10 MΩ·cm. In addition to the standard solution, other solutions and experimental water are used with helium (5.17) or ultrasound.
Degas.
5.1 Sulfuric acid. ρ(H2SO4) = 1.84 g/ml.
5.2 Ammonium chloride (NH4Cl). excellent grade pure. After drying at a constant temperature of 105 ± 5 ° C ° C, it is stored in a desiccator.
5.3 sodium hydroxide (NaOH).
5.4 Ethylenediaminetetraacetic acid disodium salt (C10H14N2Na2O8·2H2O).
5.5 Disodium hydrogen phosphate (Na2HPO4·7H2O)...
5.6 Sodium salicylate (NaC7H5O3).
5.7 Sodium nitrosoferrocyanide dihydrate (Na2[Fe(CN)5NO]·2H2O).
5.8 sodium thiosulfate (Na2S2O3).
5.9 sodium hypochlorite (NaOCl). a commercially available solution. The effective chlorine content is not less than 5.25%; see the method for determining the effective chlorine concentration.
HJ 536 Appendix A.
5.10 Buffer solution.
Weigh 30g sodium hydroxide (5.3), 25g ethylenediaminetetraacetic acid disodium salt (5.4) and 67g disodium hydrogen phosphate (5.5), dissolve
After dissolving in 800 ml of water, dilute to 1000 ml with water and shake well. The solution is stable for 1 month.
5.11 Color developer. sodium salicylate solution
Weigh 144g sodium salicylate (5.6) and 3.5g sodium nitrosoferrocyanide dihydrate (5.7) dissolved in 800ml water, dissolved
Dilute to 1000 ml with water and shake well. Stored in a brown bottle, the solution is stored at 4 ° C for 1 month.
5.12 sodium hypochlorite use solution.
Measure 60 ml of sodium hypochlorite solution (5.9), dilute to 1000 ml with water, and shake well. Available at the time of use.
5.13 Ammonia nitrogen standard stock solution. ρ(N)=1000mg/L
Weigh 3.819g of ammonium chloride (5.2) dissolved in water, dissolve it, transfer it to a 1000ml volumetric flask, dilute to volume with water and mix. The
The solution was stored at 4 ° C and was stable for 6 months. Or buy a commercially available certified reference material directly.
5.14 Ammonia nitrogen standard use solution. ρ(N)=50.0mg/L
Measure 5.00 ml of ammonia nitrogen standard stock solution (5.13), transfer to a 100 ml volumetric flask, dilute to volume with water and mix. The solution
The solution is stored at 4 ° C and is stable for 1 month.
5.15 sodium thiosulfate solution. ρ=3500mg/L
3.5 g of sodium thiosulfate (5.8) was weighed and dissolved in water and diluted to 1000 ml with water.
5.16 Aqueous filter. The pore size is 0.45 μm.
5.17 Helium. Purity ≥99.99%.
6 Instruments and equipment
6.1 Flow injection analyzer. autosampler, chemical reaction unit (ie chemical reaction module, channel. by peristaltic pump, note
The injection valve, the reaction line, etc., the detection unit (the flow path of the flow detection cell is 10 mm) and the data processing unit.
6.2 Balance. The accuracy is 0.0001g.
6.3 Centrifuge. Maximum speed 4000r/min.
6.4 Pre-distillation unit. consists of a 500ml Kay flask, nitrogen ball, straight condenser and conduit. The end of the condenser can be connected to a
A dropper of appropriate length is placed so that the tip of the outlet is immersed under the surface of the absorbing liquid.
6.5 Ultrasonic machine. frequency 40KHz.
6.6 Common instruments and equipment used in general laboratories.
7 samples
7.1 Sample collection and preservation
Samples should be collected in polyethylene or glass bottles and analyzed as soon as possible. If necessary, add sulfuric acid (5.1) to pH< 2, 5°C
The following refrigeration can be stored for 7 days; the pH of the acidified sample should be adjusted to neutral before analysis.
7.2 Preparation of samples
When the sample is clear and there is no interference such as color, turbidity and organic matter, it can be directly sampled and analyzed.
When the sample contains solid or suspended matter, the sample should be clarified by centrifugation or filtered with a filter before the machine (5.16).
filter. If the sample fails to pass the standard recovery test, it must be subjected to distillation pretreatment. See HJ 536 for the operation method.
When the sample is cloudy, colored, contains a large amount of metal ions or organic matter, it must be pre-distilled.
8 Analysis steps
8.1 Commissioning of the instrument
Install the analysis system, set the operating parameters, and operate the instrument according to the instrument manual. After starting the machine, first replace the reagent with water, check
Check the tightness of the flow path and the smoothness of the liquid flow. After the baseline has stabilized (about 15 minutes), the system begins to test
After the baseline is stabilized again, proceed to 8.2~8.4.
8.2 Calibration
8.2.1 Preparation of the standard series
Transfer the appropriate amount of ammonia nitrogen standard solution (5.14) separately, dilute to 100ml with water, and prepare the standard for 6 concentration points.
Quasi-series. Ammonia nitrogen concentrations were. 0.00 mg/L, 0.05 mg/L, 0.25 mg/L, 0.50 mg/L, 2.50 mg/L, and 5.00 mg/L, respectively.
8.2.2 Drawing of the calibration curve
Measure the appropriate standard series (8.2.1), place in the sample cup, and take the sample from the low concentration to the high concentration according to the program.
Sample, measurement. Taking the measured signal value (peak area) as the ordinate, the corresponding ammonia nitrogen concentration (in N, mg/L) is the abscissa,
Draw a calibration curve.
8.3 Determination
The measurement of the sample (7.2) was carried out under the same conditions as in the drawing of the calibration curve.
Note. If the ammonia nitrogen content of the sample exceeds the detection range of the calibration curve, the appropriate amount of the sample should be diluted and measured on the machine.
8.4 Blank test
Replace the sample with experimental water and perform a blank test in accordance with step 8.3.
9 Calculation and representation of results
9.1 Calculation of results
The mass concentration of ammonia nitrogen in the sample (in N, mg/L) is calculated according to formula (1).
Yaf
ρ −= × (1)
In the formula.
Ρ--the mass concentration of ammonia nitrogen in the sample, mg/L;
y -- determine the signal value (peak area);
a -- the intercept of the calibration curve equation;
b -- the slope of the calibration curve equation;
f -- dilution factor.
9.2 Results representation
When the measurement result is less than 1.00 mg/L, the result is retained to two decimal places; when it is greater than or equal to 1.00 mg/L, the result
Keep three significant digits.
10 Precision and accuracy
10.1 Precision
Six laboratories tested the uniform samples with ammonia nitrogen concentrations of 0.02 mg/L, 0.54 mg/L, and 2.74 mg/L.
The relative standard deviations in the laboratory are. 1.2%~8.6%, 0.3%~1.0%, 0.2%~0.7%;
The quasi-bias were. 4.6%, 1.5%, 1.7%; the repeatability limits were. 0.003mg/L, 0.010mg/L, 0.037mg/L;
The reproducibility limits were. 0.004 mg/L, 0.025 mg/L, and 0.134 mg/L, respectively.
10.2 Accuracy
Six laboratories had ammonia nitrogen concentrations of 0.54 mg/L ± 0.03 mg/L, 1.33 ± 0.03 mg/L, and 2.74 ± 0.12 mg/L, respectively.
Determination of the standard substance. relative error. 0.2% ~ 3.2%, 0.0% ~ 3.1%, 0.7% ~ 2.6%; relative error
The final values were. 1.6% ± 2.8%, 1.7% ± 2.6%, 1.7% ± 1.6%.
The concentrations of ammonia nitrogen in the six laboratories were 0.05 mg/L ~ 0.45 mg/L, 0.44 mg/L ~ 1.70 mg/L, and 1.08 mg/L, respectively.
~2.20 mg/L 3 kinds of actual samples (surface water, domestic sewage, industrial wastewater) were spiked and measured, and the recoveries were spiked.
For. 104%~114%, 98%~105%, 93.8%~104%; the final recoveries of the spiked recovery are. 108%±7.8%,
101% ± 4.8%, 98.9% ± 7.2%.
11 Quality Assurance and Quality Control
11.1 Blank test
At least 2 blank samples shall be measured for each batch of samples, and the blank value shall not exceed the method detection limit. Otherwise, the cause should be ascertained.
The sample can be measured after reanalysis until it is qualified.
11.2 Calibration validity check
A calibration curve must be drawn for each batch of samples. The correlation coefficient of the calibration curve is γ ≥ 0.995.
For each sample analyzed, a calibration curve intermediate concentration solution is used for calibration verification, and the measurement results are relatively biased.
The difference should be ≤ 5%, otherwise the calibration curve should be redrawn.
11.3 Precision Control
At least 10% of the parallel samples should be determined for each batch of samples. When the number of samples is less than 10, at least one parallel sample should be determined.
When the ammonia nitrogen concentration of the sample is ≤0.10 mg/L, the allowable relative deviation of the parallel sample is ≤20%; when the ammonia nitrogen concentration is
When 0.10~1.0mg/L, the allowable relative deviation of parallel samples is ≤15%; when the ammonia nitrogen concentration is >1.0mg/L, the allowable phase of parallel samples
The deviation is ≤10%.
11.4 Accuracy Control
At least 10% of the spiked sample shall be determined for each batch of samples. When the number of samples is less than 10, at least one spiked sample shall be determined.
The spiked recovery rate should be between 80% and 120%.
If necessary, each batch of samples shall have at least one known quality control sample, and the test results shall be in the uncertainty given by it.
Inside.
12 Precautions
12.1 Reagent and ambient temperature influence analysis results, the reagents stored in the refrigerator should be placed at room temperature (20 ± 5 ° C) before use.
The room temperature fluctuation during the analysis cannot exceed ± 2 °C.
12.2 In order to reduce baseline noise, the reagent should be kept clear and the reagent should be filtered if necessary; due to sodium hypochlorite solution (effective chlorine content)
The instability of 5.25%), pay attention to the preservation and use of the reagent, if the slope of the calibration curve is 30% lower than the normal value
(The effective chlorine content drops to 2.62%) and new reagents must be replaced. If there is a bubble in a closed chemical reaction system, it will interfere with the measurement.
Therefore, all solutions except the standard solution must be degassed, and degassed by helium for 1 min or ultrasonic degassed for 30 min.
12.3 After the analysis is completed every day, the analytical pipeline is cleaned with pure water, and the filter in the flow detection tank is removed in time.
Put it into the dryer, it is dustproof and moisture proof.
12.4 During the analysis, the detected peak-to-peak anomaly is found. In general, the flat peak is over-range and the double-peak is matrix interference.
The peak is blocked by the pump tube or the reagent is invalid.
12.5 Different types of flow analyzers can refer to this standard to select the appropriate instrument conditions.
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